The objectives of this study are to determine the factors controlling fatty acid oxidation. Carnitine is an essential cofactor for long-chain fatty acid oxidation and may serve as an important regulator. The enzymatic hydroxylation of trimethyllysine to form 3-hydroxytrimethyllysine and the conversion of 3-hydroxytrimethyllysine into trimethylaminobutyrate are being characterized. High pressure liquid chromatographic analytical methods are being developed to measure trimethyllysine, 3-hydroxytrimethyllysine, trimethylaminobutyrate and carnitine. We are systematically studying the effects of exogenous carnitine on in vivo fatty acid oxidation and the effects of carnitine on rat liver mitochondrial oxidation of fatty acids in vitro. Carnitine palmitoyltransferase deficiency in skeletal muscle of patients with ketotic lipoid myopathies are being studied functionally and enzymatically. The enzyme carnitine palmitoyltransferase is being purified. Kinetic analysis has shown two different types and we are further characterizing these differences.